A Bi-directional Promoter at The Upstream of pp38 Gene from Marek''''s Disease Virus
马立克氏病病毒pp38基因上游的一个双向启动子研究

Marek's disease virus(MDV)'s replicating origin is at the upstream of pp38 gene. On both sides of the region, there are several conserved promoter motifs such as TATA-box, CAAT-box, etc, which is regarded as a bi-directional promoter and enhancer. In order to validate the divergent promoting activity in vivtro, we cloned MDV pp38 gene open reading frame(ORF) into pUC18 vector, and constructed pUC-pp38 as a basic plasmid. The 789bp PCR fragment which contains the complete sequences of MDV's replicating origin was cloned at the upstream of pp38 gene in pUC-pp38 at two different directions. The positive clones named as pPro fpp38 and pPro rpp38 were transfected into chicken embryo fibroblast(CEF) cells. 24 hours after the transfection, green fluorescence can been seen on the cytoplasm of CEF in immunofluorecent assay(IFA). 48 hours and on after the transfection, the IFA positive cells will be up to 50% and the expression level can be maintained for a few days. The results show that this region has bi-directional promoting activity. 320bp was confirmed as the core sequence of this promoter with PCR technique.